Sales of previously owned U.S. homes in March unexpectedly fell for the third time in the last four months, showing an uneven recovery in the housing market.

Purchases dropped 2.6 percent to a 4.48 million annual rate from 4.6 million in February, the National Association of Realtors reported today in Washington. The median forecast of economists in a Bloomberg News survey called for an increase to 4.61 million. In January, sales at a 4.63 million rate were the strongest since May 2010.

Ah, yes — unexpectedly. Why such a surprise? Apparently, analysts didn’t figure in the decline in job creation last month:

Residential real estate remains the economy’s soft spot, challenged by stricter lending standards, lower home values and the threat of more foreclosures. An improved labor market and mortgage rates near historic lows have yet to stoke bigger gains in demand.

The description of an “improved labor market” applied more in February than it did in March. Last month, the US only added 120,000 jobs, barely enough to keep up with population growth. Even before that, the previous three months added around 650,000 jobs in the aggregate, which means actual growth above population increase of about 300,000 jobs — which wouldn’t greatly increase demand in the housing market, but shouldn’t result in a decrease in demand. First-time buyers still only account for a third of these purchases, when the normal level is around 40%, according to Bloomberg News. That’s an indication of a lack of confidence among younger adults.

Now that the churn rate on jobs has increased, as evidenced in the rise in weekly initial jobless claims, confidence and demand will likely decline a bit. The soon-to-arrive flood of foreclosures and short sales might stoke demand for bargain hunters who have waited patiently for the settlement to take effect. That may give a false impression of demand, though, as one analyst warns:

Investors accounted for 21 percent of purchases last month, down from 23 percent in February, today’s data showed. Such figures suggest the recovery in housing isn’t broad-based, said Jay McCanless, a housing analyst with Guggenheim Securities LLC in Nashville, Tennessee.

“We’ve seen investors and cash sales continue to be anywhere from 20 percent to 33 percent of monthly sales,” McCanless said. “That may be giving the appearance that there’s more activity, more demand for housing than may actually be the case.”

Cash buyers have been a big factor in the local Twin Cities foreclosure/short sale market for the past year already. That will also likely spike upward when the pent-up foreclosures come to market, but the inventory will allow others to play in the same market, too. We may not get a clear idea of how the resale market looks for several months after the release, so new-home sales and startups might give us a better indicator to watch.